Polyphenylene ethers are excellent in processability and productivity. They can be molded by molding techniques, such as melt injection molding and melt extrusion molding, into products or parts of desired shapes with efficient productivity. Therefore, they have been widely used as materials for products and parts in the electrical and electronic fields and other various industrial fields, and foods and packaging fields.
Recently, as a result of diversified products and parts particularly in the electrical and electronic fields, automobile field and other various industrial fields, demands for resin materials have also become diverse.
To meet the demands, combining different types of materials and using polymer alloy technology that combines various existent high polymer materials, have led to the development of resin materials that have properties not possessed by the existent materials.
While regular polyphenylene ethers have excellent heat resistance and mechanical properties, they are poor in compatibility with other materials and the choices of counterpart materials to combine with are limited. In particular, polyphenylene ethers have very poor compatibility with highly polar materials, such as polyamide, and to combine them with such resins requires functionalized polyphenylene ethers.
Among functionalized polyphenylene ethers, a polyphenylene ether having an epoxy group is particularly preferred. This is because an epoxy group is highly reactive and easily reacts with various functional groups, such as amino, carboxyl and phenolic hydroxyl groups, and hence abundant types of different polymers are available to combine with. For epoxidized polyphenylene ethers, WO 87/07281, WO 00/52074, JP 7-5818 B, and JP 3-6185 B disclose methods of reacting polyphenylene ethers with low-molecular-weight olefin compounds containing a carbon-carbon double bond or triple bond together with an epoxy group; for example, glycidyl methacrylate and glycidyl acrylate. In these methods, however, since the epoxy group of the low-molecular-weight olefin compound directly reacts with the phenolic hydroxyl group of the polyphenylene ether, the number of epoxy groups that can be efficiently introduced into the high polymer chain is small and thus-prepared epoxidized polyphenylene ether exhibits poor reactivity when it is blended with a different kind of polymer. Therefore, such a blend is not much different in material property from a simple blend of polyphenylene ether with a different kind of polymer.
JP 5-279568 A discloses a method of obtaining an epoxidized polyphenylene ether by reacting a compound having one or two epoxy groups in the molecule with a polyphenylene ether. However, because the reaction is carried out either in a solvent in which the polyphenylene ether is soluble, or where polyphenylene ether is dissolved in the epoxy compound, this method, as a result of the reaction among the epoxy groups, produces crosslinked polyphenylene ether or gelled product, that is insoluble in the solvent; hence impregnating therewith a substrate material, such as a glass fiber, becomes difficult in the process for the production of printed substrate.
JP 5-214129 A describes a method of blending a polyphenylene oxide with a liquid epoxy substance without any solvent. In the method, however, the blend of the polyphenylene ether and the liquid epoxy material forms a paste and thus produces crosslinked polyphenylene ether or gelled product that is insoluble in a solvent, thereby making impregnation of a substrate material, such as a glass fiber, with the product difficult in the process for the production of printed substrate.
Polyphenylene ether resins are suitable materials for printed substrate and insulating sealants for electrical and electronic devices owing to their heat-resistance to high temperatures and low dielectric constant. On the other hand, they have a shortcoming of having low solvent resistance to halogenated solvents, such as trichloroethylene, and aromatic solvents, such as toluene. Thus, in their application to electronic materials, it is required to improve their solvent resistance without impairing the low dielectric property and high heat resistance by crosslinking and curing polyphenylene ethers. As conventional means for crosslinking and curing polyphenylene ethers, methods of adding an excess of a thermosetting resin, such as an epoxy resin, or a crosslinking compound, such as triallyl isocyanurate, have been employed, but the low dielectric property and high heat resistance inherent in polyphenylene ethers cannot be achieved by these methods. For example, polyphenylene ether/polyepoxide compositions are disclosed in JP 6-206984 A, JP 6-17457 B, and JP 11-302529 A. In the methods, since crosslinking and curing are effected by adding an excess of polyepoxide to polyphenylene ether, the low dielectric property and high heat resistance inherent in polyphenylene ethers cannot be achieved. JP 11-236430 A discloses a composition composed of polyphenylene ether/brominated epoxy compound/allyl compound; however, this poses a problem that the low dielectric property inherent in polyphenylene ethers is impaired because of large contents of the epoxy compound and allyl compound in the composition.
The invention relates to a functionalized polyphenylene ether which provides polymer alloys with excellent mechanical properties when blended with other resins and yet provides cured products with hardly impared low dielectric property and high heat resistance inherent in polyphenylene ethers.